Nectin-4 cis-interacts with ErbB2 and its trastuzumab-resistant splice variants, enhancing their activation and DNA synthesis

Unlocking the Potential: Biomarkers of Response to Antibody-Drug Conjugates

Antibody-drug conjugates (ADCs) have reshaped the cancer treatment landscape across a variety of different tumor types. ADCs' peculiar pharmacologic design combines the cytotoxic properties of chemotherapeutic agents with the selectivity of targeted therapies. At present, the approval of many ADCs used in clinical practice has not always been biomarker-driven. Indeed, predicting ADCs' activity and toxicity through the demonstration of specific biomarkers is still a great unmet need, and the identification of patients who can derive significant benefit from treatment with ADCs may often be uncertain. With the lack of robust predictive biomarkers to anticipate primary, intrinsic resistance to ADCs and no consolidated biomarkers to aid in the early identification of treatment resistance (ie, acquired resistance), the determination of precise biologic mechanisms of ADC activity and safety becomes priority in the quest for better patient-centric outcomes. Of great relevance, whether the target antigen expression is a determinant of ADCs' primary activity is still to be clarified, and available data remain quite controversial. Antigen expression assessment is typically performed on tissue biopsy, hence only providing information on a specific tumor site, therefore unable to capture heterogeneous patterns of tumor antigen expression. Quantifying the expression of the target antigen across all tumor sites would help better understand tumor heterogeneity, whereas molecularly characterizing tumor-intrinsic features over time might provide information on resistance mechanisms. In addition, toxicity can represent a critical concern, since most ADCs have a safety profile that resembles that of chemotherapies, with often unique adverse events requiring special management, possibly because of the differential in pharmacokinetics between the small-molecule agent versus payload of a similar class (eg, deruxtecan conjugate-related interstitial lung disease). As such, the identification of robust predictive biomarkers of safety and activity of ADCs has the potential to improve patient selection and enrich the population of patients most likely to derive a substantial clinical benefit, especially in those disease settings where different ADCs happen to be approved in competing clinical indications, with undefined biomarkers to make precise decision making and unclear data on how to sequence ADCs. At this point, the identification of clinically actionable biomarkers in the space of ADCs remains a top research priority.

Therapeutic prospects of nectin-4 in cancer: applications and value

Nectin-4 is a Ca2+-independent immunoglobulin-like protein that exhibits significantly elevated expression in malignant tumors while maintaining extremely low levels in healthy adult tissues. In recent years, overexpression of Nectin-4 has been implicated in tumor occurrence and development of various cancers, including breast cancer, urothelial cancer, and lung cancer. In 2019, the Food and Drug Administration approved enfortumab vedotin, the first antibody-drug conjugate targeting Nectin-4, for the treatment of urothelial carcinoma. This has emphasized the value of Nectin-4 in tumor targeted therapy and promoted the implementation of more clinical trials of enfortumab vedotin. In addition, many new drugs targeting Nectin-4 for the treatment of malignant tumors have entered clinical trials, with the aim of exploring potential new indications. However, the exact mechanisms by which Nectin-4 affects tumorigenesis and progression are still unclear, and the emergence of drug resistance and treatment-related adverse reactions poses challenges. This article reviews the diagnostic potential, prognostic significance, and molecular role of Nectin-4 in tumors, with a focus on clinical trials in the field of Nectin-4-related tumor treatment and the development of new drugs targeting Nectin-4.

Nectin-4 has emerged as a compelling target for breast cancer

The incidence of breast cancer in women has increased year by year, becoming one of the most common malignant tumors in females worldwide. Most patients can be treated with surgery and endocrine drugs, but there are still some patients who lack effective treatment, such as triple-negative breast cancer (TNBC). Nectin-4, a protein encoded by poliovirus receptor-associated protein 4, is a Ca2+-independent immunoglobulin-like protein. It is mainly involved in the adhesion between cells. In recent years, studies have found that Nectin-4 is overexpressed in breast cancer and several other malignancies. Otherwise, several monoclonal antibodies and inhibitors targeting Nectin-4 have shown prosperous outcomes, so Nectin-4 has great potential to be a therapeutic target for breast cancer. The present review systematically describes the significance of Nectin-4 in each aspect of breast cancer, as well as the molecular mechanisms of these aspects mediated by Nectin-4. We further highlight ongoing or proposed therapeutic strategies for breast cancer specific to Nectin-4.

Antibody-drug conjugates in HER-2 negative breast cancers with poor prognosis

Antibody drug conjugates (ADCs) comprise a rapidly growing class of targeted drugs that selectively deliver a cytotoxic agent to cancer cells, reducing the side effects associated with conventional chemotherapy. Breast cancer (BC) is a heterogeneous entity. The need for effective therapies for HER-2 negative BCs with poor prognosis, such as triple-negative or endocrine-resistant BC, remains unmet due to the lack of potential targets for treatments. These BC subtypes are not candidates for hormonal or anti-HER-2 agents. However, ongoing clinical trials exploring the use of ADCs with a wide range of targets have shown potential for this treatment modality. In this review, we present the current state of knowledge regarding the role of ADC and speculate on novel approaches including ADC combination therapies, new molecular targets, and the role of other subclasses of ADCs (bicycle drug conjugates, bispecific ADCs, immune modulating ADCs) in this clinical scenario.

Nectin-4 as a Predictive Marker for Poor Prognosis of Endometrial Cancer with Mismatch Repair Impairment

The adhesion molecule Nectin-4 is a new potential therapeutic target for different types of cancer; however, little is known about its diagnosis significance in endometrial cancer (EC). We found that Nectin-4 expression was significantly higher in EC tissues than in nonadjacent normal tissue. The area under the receiver operating characteristic curve value of 0.922 indicated good diagnostic accuracy for Nectin-4 expression in EC. Furthermore, Nectin-4 expression was associated with DNA mismatch repair (MMR) protein deficiency. Notably, the high Nectin-4 expression group of patients with MSH2/6-deficient EC had shorter progression-free survival than that of the low Nectin-4 expression group. The number of lymphovascular space invasion-positive patients in groups with MMR deficiency and high Nectin-4 expression was also increased compared with that in the low Nectin-4 expression group. Bioinformatics analysis revealed that alteration in Nectin-4 and MMR genes is associated with Nectin-4 expression in EC. To the best of our knowledge, this is the first study to show that Nectin-4 expression may be a potential biomarker for EC diagnosis and that high Nectin-4 expression in MMR-deficient patients with EC can predict short progression-free survival, thus providing clues to identify patients for adjuvant therapy.

Future potential targets of antibody-drug conjugates in breast cancer

Metastatic breast cancer (BC) remains an incurable disease. Besides endocrine and targeted agents, chemotherapy is still a relevant therapeutic option for this disease. Recently, antibody-drug conjugates (ADCs) have shown to overcome the lack of tumor specificity and systemic toxicity typically associated with traditional chemotherapies, thus improving the therapeutic index. To effectively exploit this technological breakthrough, identification of optimal target antigens (Ags) is of utmost importance. To make the ideal target, differential expression of target Ags between healthy and cancer tissues, as well as specific mechanisms of ADC internalization after Ag-antibody interaction are required. Therefore, several in silico strategies to identify and characterize new promising candidate Ags have been developed. If initial in vitro and in vivo positive data are documented, thus providing a biological rationale for further Ag investigation, early phase clinical trials are designed. In BC, these strategies have already led to the development of effective ADCs, namely trastuzumab emtansine (T-DM1), trastuzumab deruxtecan (T-DXd) and sacituzumab govitecan (SG), primarily targeting HER2 and TROP-2. However, promising new Ags are currently under investigation, with encouraging results especially coming from targeting HER3, FRα, Tissue Factor, LIV-1, ROR1-2, and B7-H4. In this review, we describe the landscape of emergent and future potential targets (i.e., other than HER2 and TROP-2) investigated in BC for ADC development. Predominant target expression, function, preclinical rationale, potential clinical implication, as well as preliminary clinical trial results are provided.

Nectins and Nectin-like Molecules in Colorectal Cancer: Role in Diagnostics, Prognostic Values, and Emerging Treatment Options: A Literature Review

In 2020, colorectal cancer was the third most common type of cancer worldwide with a clearly visible increase in the number of cases each year. With relatively high mortality rates and an uncertain prognosis, colorectal cancer is a serious health problem. There is an urgent need to investigate its specific mechanism of carcinogenesis and progression in order to develop new strategies of action against this cancer. Nectins and Nectin-like molecules are cell adhesion molecules that take part in a plethora of essential processes in healthy tissues as well as mediating substantial actions for tumor initiation and evolution. Our understanding of their role and a viable application of this in anti-cancer therapy has rapidly improved in recent years. This review summarizes the current data on the role nectins and Nectin-like molecules play in colorectal cancer.

Small-molecule inhibitors, immune checkpoint inhibitors, and more: FDA-approved novel therapeutic drugs for solid tumors from 1991 to 2021

The United States Food and Drug Administration (US FDA) has always been a forerunner in drug evaluation and supervision. Over the past 31 years, 1050 drugs (excluding vaccines, cell-based therapies, and gene therapy products) have been approved as new molecular entities (NMEs) or biologics license applications (BLAs). A total of 228 of these 1050 drugs were identified as cancer therapeutics or cancer-related drugs, and 120 of them were classified as therapeutic drugs for solid tumors according to their initial indications. These drugs have evolved from small molecules with broad-spectrum antitumor properties in the early stage to monoclonal antibodies (mAbs) and antibody‒drug conjugates (ADCs) with a more precise targeting effect during the most recent decade. These drugs have extended indications for other malignancies, constituting a cancer treatment system for monotherapy or combined therapy. However, the available targets are still mainly limited to receptor tyrosine kinases (RTKs), restricting the development of antitumor drugs. In this review, these 120 drugs are summarized and classified according to the initial indications, characteristics, or functions. Additionally, RTK-targeted therapies and immune checkpoint-based immunotherapies are also discussed. Our analysis of existing challenges and potential opportunities in drug development may advance solid tumor treatment in the future.

Histology-agnostic approvals for antibody-drug conjugates in solid tumours: is the time ripe?

Several antibody-drug conjugates (ADCs) have been recently approved to treat solid tumours. Since ADCs seem to have activity in multiple malignancies sharing the expression of a specific antigen, they may be mirroring the experience of histology-agnostic-targeted treatments. So, the possibility to interpret the activity of some ADCs across different cancer types in a biomarker-driven perspective arises. However, relevant biological, methodological, and regulatory challenges should be highlighted and addressed, in order to grant ADCs biomarker-driven regulatory approvals in the next future. In this review, we discuss challenges and opportunities posed by the pan-histological expansion of ADCs in solid tumours. In particular, we provide an overview about technological and manufacturing advancements; we offer up-to-date highlights of the current evidence from clinical trials investigating ADCs in solid tumours; we discuss the need for the identification of optimal predictive biomarkers, as well as major methodological, statistical, and regulatory considerations for a biomarker-driven histology-agnostic approach.

Stimulatory role of nectin-4 and p95-ErbB2 in multilayered T47D cell proliferation

Multilayered proliferation in an adherent culture as well as proliferation in a suspension culture is a characteristic feature of cancer cells. We previously showed using T47D human mammary cancer cells that nectin-4, upregulated in many cancer cells, cis-interacts with ErbB2 and its trastuzumab-resistant splice variants, p95-ErbB2 and ErbB2ΔEx16, and enhances DNA synthesis mainly through the PI3K-AKT pathway in an adherent culture. We showed here that only the combination of nectin-4 and p95-ErbB2, but not that of nectin-4 and ErbB2 or that of nectin-4 and ErbB2ΔEx16, cooperatively enhanced multilayered T47D cell proliferation through the Hippo pathway-mediated SOX2 gene expression in an adherent culture. T47D cells expressed the components of the apical junctional complex (AJC) consisting of adherens junctions (AJs) and tight junctions and cell polarity molecules, but not the AJ component afadin. The AJC and apicobasal polarity were disorganized in T47D cells in a monolayer and T47D cells stably expressing both nectin-4 and p95-ErbB2 in multilayers. These results indicate that nectin-4 and p95-ErbB2 play a stimulatory role in multilayered proliferation in an adherent culture.

Nectin-4: a Novel Therapeutic Target for Skin Cancers

OPINION STATEMENT

Nectin-4 is a tumor-associated antigen that is highly expressed on various cancer cells, and it has been further proposed to have roles in tumor development and propagation ranging from cellular proliferation to motility and invasion. Nectin-4 blockade reduces tumor proliferation and induces apoptosis in several malignancies. Nectin-4 has been used as a potential target in antibody-drug conjugate (ADC) development. Enfortumab vedotin, an ADC against Nectin-4, has demonstrated efficacy against solid tumor malignancies. Enfortumab vedotin has received US Food and Drug Administration approval for treating urothelial cancer. Furthermore, the efficacy of ADCs against Nectin-4 against solid tumors other than urothelial cancer has been demonstrated in preclinical studies, and clinical trials examining the effects of enfortumab vedotin are ongoing. Recently, Nectin-4 was reported to be highly expressed in several skin cancers, including malignant melanoma, cutaneous squamous cell carcinoma, and extramammary Paget's disease, and involved in tumor progression and survival in retrospective studies. Nectin-4-targeted therapies and ADCs against Nectin-4 could therefore be novel therapeutic options for skin cancers. This review highlights current knowledge on Nectin-4 in malignant tumors, the efficacy of enfortumab vedotin in clinical trials, and the prospects of Nectin-4-targeted agents against skin cancers.

Antibody-Drug Conjugates in Urothelial Carcinoma: A New Therapeutic Opportunity Moves from Bench to Bedside

Significant progress has been achieved over the last decades in understanding the biology and mechanisms of tumor progression in urothelial carcinoma (UC). Although the therapeutic landscape has dramatically changed in recent years with the introduction of immune checkpoint inhibitors, advanced UC is still associated with rapidly progressing disease and poor survival. The increasing knowledge of the pathogenesis and molecular pathways underlying cancer development and progression is leading the introduction of target therapies, such as the recently approved FGFR inhibitor Erdafitinib, or the anti-nectin 4 antibody drug-conjugate Enfortumab vedotin. Antibody drug conjugates represent an innovative therapeutic approach that allows the combination of a tar get-specific monoclonal antibody covalently conjugated via a linker to a cytotoxic agent (payload). UC is a perfect candidate for this therapeutic approach since it is particularly enriched in antigen expression on its surface and each specific antigen can represent a potential therapeutic target. In this review we summarize the mechanism of action of ADCs, their applications in localized and metastatic UC, the main mechanisms of resistance, and future perspectives for their use in clinical practice.

Nectin-2 in general and in the brain

Nectins are immunoglobulin-like cell adhesion molecules constituting a family with four members, nectin-1, nectin-2, nectin-3, and nectin-4. In the brain, nectin-2 as well as nectin-1 and nectin-3 are expressed whereas nectin-4 is hardly expressed. In the nervous system, physiological functions of nectin-1 and nectin-3, such as synapse formation, mossy fiber trajectory regulation, interneurite affinity, contextual fear memory formation, and stress-related mental disorders, have been revealed. Nectin-2 is ubiquitously expressed in non-neuronal tissues and various nectin-2 functions in non-nervous systems have been extensively investigated, but nectin-2 functions in the brain have not been revealed until recently. Recent findings have revealed that nectin-2 is expressed in the specific areas of the brain and plays important roles, such as homeostasis of astrocytes and neurons and the formation of synapses. Moreover, a single nucleotide polymorphism in the human NECTIN2 gene is associated with Alzheimer's disease. We here summarize recent progress in our understanding of nectin-2 functions in the brain.

Analysis of miRNA expression profile in lung tissues of an intermittent hypoxia rat model

We screened key miRNAs in an intermittent hypoxia rat model and explored the biological roles of downstream target genes and related regulatory pathways. We analyzed the expression profile of miRNAs in the lung tissues of rats in the 5 % (IH1), 7.5 % (IH2), 10 % (IH3), 12.5 % (IH4) oxygen concentration and negative control (NC) groups and identified common miRNAs. Multiple differentially expressed miRNAs were detected, and intersection of their expression profiles yielded 10 common miRNAs with 929 target genes mainly distributed in the nucleus. Molecular functions pertained mainly to the activation of transcription factors, while biological processes focused on cell interaction and signal transduction. Among signaling pathways, the top 5 included the LKB1 signaling, nectin adhesion, and S1P pathways. 8 of 10 common miRNAs had excellent diagnostic value for detecting intermittent hypoxia. The miRNAs binds to the target gene might play a key role in the pathophysiological process of OSA through the LKB1/AMPK and S1P/Akt/eNOS signaling pathways.

Emerging roles of the nectin family of cell adhesion molecules in tumour-associated pathways

Tumour cells achieve maximum survival by modifying cellular machineries associated with processes such as cell division, migration, survival, and apoptosis, resulting in genetically complex and heterogeneous populations. While nectin and nectin-like cell adhesion molecules control development and maintenance of multicellular organisation in higher vertebrates by mediating cell-cell adhesion and related signalling processes, recent studies indicate that they also critically regulate growth and development of different types of cancers. In this review, we detail current knowledge about the role of nectin family members in various tumours. Furthermore, we also analyse the seemingly opposing roles of some members of nectin family in tumour-associated pathways, as they function as both tumour suppressors and oncogenes. Understanding this functional duality of nectin family in tumours will further our knowledge of molecular mechanisms regulating tumour development and progression, and contribute to the advancement of tumour diagnosis and therapy.

Targeting nectin-4 by antibody-drug conjugates for the treatment of urothelial carcinoma

INTRODUCTION

Nectin-4 is a tumor-associated antigen overexpressed in urothelial carcinoma and several other malignancies. It has emerged as a compelling target for novel tumor-directed therapies, particularly as a component of antibody-drug conjugates (ADCs), a growing class of anti-cancer therapeutic agents. Development of nectin-4-directed therapies has been led by enfortumab vedotin (EV), an ADC comprised of a fully human monoclonal antibody specific for nectin-4 conjugated via a cleavable linker to the microtubule inhibitor MMAE. EV was approved in 2019 as a first-in-class agent for the treatment of urothelial carcinoma.

AREAS COVERED

This article discusses general principles relevant to ADC design and our current understanding of nectin-4 in normal physiology and malignancy, followed by a review of the development of EV as well as additional drug conjugate strategies targeting nectin-4.

EXPERT OPINION

EV offers proof-of-concept for the clinical utility of nectin-4-directed therapies and provides further support for ADCs as an important class of anti-cancer agents. Future development of nectin-4-targeted approaches will benefit from a deeper understanding of nectin-4 biology in both health and disease, as well as a detailed exploration of the mechanisms underlying therapeutic activity and resistance.

Fibroblast Growth Factor Receptors (FGFRs) and Noncanonical Partners in Cancer Signaling

Increasing evidence indicates that success of targeted therapies in the treatment of cancer is context-dependent and is influenced by a complex crosstalk between signaling pathways and between cell types in the tumor. The Fibroblast Growth Factor (FGF)/FGF receptor (FGFR) signaling axis highlights the importance of such context-dependent signaling in cancer. Aberrant FGFR signaling has been characterized in almost all cancer types, most commonly non-small cell lung cancer (NSCLC), breast cancer, glioblastoma, prostate cancer and gastrointestinal cancer. This occurs primarily through amplification and over-expression of FGFR1 and FGFR2 resulting in ligand-independent activation. Mutations and translocations of FGFR1-4 are also identified in cancer. Canonical FGF-FGFR signaling is tightly regulated by ligand-receptor combinations as well as direct interactions with the FGFR coreceptors heparan sulfate proteoglycans (HSPGs) and Klotho. Noncanonical FGFR signaling partners have been implicated in differential regulation of FGFR signaling. FGFR directly interacts with cell adhesion molecules (CAMs) and extracellular matrix (ECM) proteins, contributing to invasive and migratory properties of cancer cells, whereas interactions with other receptor tyrosine kinases (RTKs) regulate angiogenic, resistance to therapy, and metastatic potential of cancer cells. The diversity in FGFR signaling partners supports a role for FGFR signaling in cancer, independent of genetic aberration.

Nectin-4 and p95-ErbB2 cooperatively regulate Hippo signaling-dependent SOX2 gene expression, enhancing anchorage-independent T47D cell proliferation

Nectin-4, upregulated in various cancer cells, cis-interacts with ErbB2 and its trastuzumab-resistant splice variants, p95-ErbB2 and ErbB2∆Ex16, enhancing DNA synthesis through the PI3K-AKT signaling in human breast cancer T47D cells in an adherent culture. We found here that nectin-4 and p95-ErbB2, but not nectin-4 and either ErbB2 or ErbB2∆Ex16, cooperatively enhanced SOX2 gene expression and cell proliferation in a suspension culture. This enhancement of T47D cell proliferation in a suspension culture by nectin-4 and p95-ErbB2 was dependent on the SOX2 gene expression. In T47D cells, nectin-4 and any one of p95-ErbB2, ErbB2, or ErbB2∆Ex16 cooperatively activated the PI3K-AKT signaling, known to induce the SOX2 gene expression, to similar extents. However, only a combination of nectin-4 and p95-ErbB2, but not that of nectin-4 and either ErbB2 or ErbB2∆Ex16, cooperatively enhanced the SOX2 gene expression. Detailed studies revealed that only nectin-4 and p95-ErbB2 cooperatively activated the Hippo signaling. YAP inhibited the SOX2 gene expression in this cell line and thus the MST1/2-LATS1/2 signaling-mediated YAP inactivation increased the SOX2 gene expression. These results indicate that only the combination of nectin-4 and p95-ErbB2, but not that of nectin-4 and either ErbB2 or ErbB2∆Ex16, cooperatively regulates the Hippo signaling-dependent SOX2 gene expression, enhancing anchorage-independent T47D cell proliferation.

The biology and rationale of targeting nectin-4 in urothelial carcinoma

Bladder cancer is the tenth most common cancer type worldwide. Urothelial carcinoma is the most common type of bladder cancer and accounts for 90% of bladder cancer cases in the USA and Europe. Novel approaches are needed to improve patient outcomes. Nectin-4 is a tumour-associated antigen found on the surface of most urothelial carcinoma cells. In the antibody-drug conjugate enfortumab vedotin, human anti-nectin-4 antibody is linked to the cytotoxic microtubule-disrupting agent monomethyl auristatin E. In ongoing phase I, II and III clinical trials, enfortumab vedotin has been evaluated as a monotherapy and in combination with a checkpoint inhibitor and/or chemotherapy in locally advanced and metastatic urothelial carcinoma. Encouraging data from the phase II study resulted in the FDA granting accelerated approval for enfortumab vedotin in December 2019 for patients with locally advanced or metastatic urothelial carcinoma who were previously treated with platinum and a checkpoint inhibitor therapy. Moreover, data from a phase I study led to the FDA granting breakthrough therapy designation to enfortumab vedotin combined with pembrolizumab as a first-line treatment in February 2020 for cisplatin-ineligible patients with locally advanced or metastatic urothelial carcinoma. Results of ongoing and future combination studies of enfortumab vedotin with immunotherapy and other novel agents are eagerly awaited.

NECTIN4 Expression in Extramammary Paget's Disease: Implication of a New Therapeutic Target

Extramammary Paget's disease (EMPD) is a rare skin cancer arising in the anogenital area. Most EMPD tumors remain dormant as in situ lesions, but the outcomes of patients with metastatic EMPD are poor because of the lack of effective systemic therapies. Nectin cell adhesion molecule 4 (NECTIN4) has attracted attention as a potential therapeutic target for some cancers. Urothelial cancer is one such cancer, and clinical trials of enfortumab vedotin, a drug-conjugated anti-NECTIN4 antibody, are ongoing. However, little is known regarding the role of NECTIN4 in EMPD. In this study, we conducted immunohistochemical analysis of NECTIN4 expression in 110 clinical EMPD samples and normal skin tissue. In normal skin, positive signals were observed in epidermal keratinocytes (particularly in the lower part of the epidermis), eccrine and apocrine sweat glands, inner and outer root sheaths, and matrix of the hair follicles. The most EMPD lesions exhibited strong NECTIN4 expression, and high NECTIN4 expression was significantly associated with increased tumor thickness, advanced TNM stage, and worse disease-specific survival. These results support the potential use of NECTIN4-targeted therapy for EMPD. Our report contributes to the better understanding of the pathobiology of NECTIN4 in the skin and the skin-related adverse effects of NECTIN4-targeted therapy.